Surface Of Sleeve Research Articles

The influence of modification of the geometry of the front surface of the RFSSW tool inner sleeve on the fatigue life of joints during joining clad sheets made of aluminum alloy 2024-T3

AbstractRefill Friction Stir Spot Welding (RFSSW) has a number of advantages that make it a possible alternative to riveting and resistance welding in aerospace structures, the automotive industry and other applications. Adequate determination of technological parameters which ensure the desired properties of welds and their functioning in various operating conditions requires, among others, appropriate fatigue life of connections. The article presents the results of comparative tests of the mechanical properties of welds (load-bearing capacity and fatigue life at selected three load levels) made with a basic tool (G0) and a tool with a modified geometry (G4). The samples were made of 1.27 mm thick clad sheets of 2024-T3 aluminum alloy with an additional oxide anodic coating. It has been shown that the modified geometry of the working surface of the inner sleeve of the RFSSW tool improves the conditions and course of the plasticization and stirring process of the joined materials. The use of a G4 geometry tool allowed for approximately 30% higher joint load-bearing capacity and approximately twice as long fatigue life (at lower load levels) compared to welds made with the G0 tool.

Numerical simulation of friction characteristics of bionic flexible contact surface of front axle rocker arm sleeve of car

Based on the finite element software ABAQUS, the friction process of the flexible friction pair of the front axle rocker bushing of a car with a convex structure similar to the mantis head is established.The finite element model of the process is constructed and its friction characteristics are verified. By selecting a suitable hyperelastic constitutive model and changing the size of the convex structure on the surface of the sleeve,The simulation analysis of the mechanical characteristics of the flexible friction pair in radial and torsional directions shows that the bionic convex hull design changes the maximum stress of the bushing when it is subjected to force.The force and strain position are adjusted to reduce the possibility of cracking of the rubber bushing; the contact friction force and friction coefficient of the bionic bushing surface are significantly reduced, and the type 2 modelThe drag reduction and wear resistance of the profiled surface are the best.

Fault Analysis of 35kV Outdoor Vacuum Circuit Breaker Pillar Porcelain Sleeve

In order to further clarify the failure mechanism of the pillar porcelain insulator, the field inspection, the microscopic morphology analysis and material analysis of the ceramic shell of the pillar under a 35kV outdoor vacuum circuit breaker were carried out. The results show that the direct cause of the failure is the discharge between the high voltage conductor inside the porcelain sleeve and the weak part of the porcelain sleeve, and the high temperature arc leads to the bursting of the porcelain sleeve. The indirect cause of the failure is the loose porcelain of the porcelain sleeve, the existence of internal layering, uneven composition and micro-pores and other macro and micro defects, and the original defects of the inner surface of the porcelain sleeve, such as local unglazed and poor quality of the porcelain sleeve manufacturing process. In the long-term outdoor operation, the external moisture and gas penetrate into the porcelain sleeve, which leads to the deterioration of the insulation performance of the porcelain sleeve, and eventually leads to failure.

Large-Scale Tactile Detection System Based on Supervised Learning for Service Robots Human Interaction

In this work, a large-scale tactile detection system is proposed, whose development is based on a soft structure using Machine Learning and Computer Vision algorithms to map the surface of a forearm sleeve. The current application has a cylindrical design, whose dimensions intend to be like a human forearm or bicep. The model was developed assuming that deformations occur only at one section at a time. The goal for this system is to be coupled with the CHARMIE robot, a collaborative robot for domestic and medical environments. This system allows the contact detection of the entire forearm surface enabling interaction between a Human Being and a robot. A matrix with sections can be configured to present certain functionalities, allowing CHARMIE to detect contact in a particular section, and thus perform a specific behaviour. After building the dataset, an Artificial Neural Network (ANN) was created. This network was called Section Detection Network (SDN), and through Supervised Learning, a model was created to predict the contact location. Furthermore, Stratified K-Fold Cross Validation (SKFCV) was used to divide the dataset. All these steps resulted in Neural Network with a test data accuracy higher than 80%. Regarding the real-time evaluation, a graphical interface was structured to demonstrate the predicted class and the corresponding probability. This research concluded that the method described has enormous potential to be used as a tool for service robots allowing enhanced human-robot interaction.

THEORETICAL SUBSTANTIATION OF CAVITATION WEAR INTENSITY REDUCTION OF CYLINDER SLEEVE WALLS BY APPLICATION OF ANTI-CAVITATION COATING

One of the ways to increase service life of internal combustion engines is to reduce cavitation wear intensity of the outer wall of the cylinder sleeves. The most promising, at present, method is application of anti-cavitation coating on the outer surface of the cylinder sleeve. The aim of the research was to establish theoretical dependencies that allow to substantiate the properties and thickness of the anti-cavitation material applied to the outer wall of the cylinder sleeve. Theoretical studies of cavitation wear intensity along the destruction depth of the cylinder sleeve wall established that when choosing cavitation-resistant materials, it is necessary to have regard to material structure and give preference to those materials that are characterized by high resistance to microvolumes of plastic deformation under microshock action and are capable of withstanding operating modes over a wide temperature range. The materials of the polytetrafluoroethylene group - fluoroplasts - most fully meet these requirements. Studies of the fluoroplastic coating applied to the outer wall of the cylinder sleeve, using the obtained theoretical dependencies, showed that the minimum wear rate of the cylinder sleeve of 0.0006 mm3/cycle is achieved with a fluoroplastic coating thickness of the outer surface of the cylinder sleeve with a thickness of 1.8 mm. In this case, the difference in heating of a typical sleeve and a sleeve with a fluoroplastic coating with an increase of the heating temperature of the inner wall of the sleeve decreases from 15% at a temperature of 50 °C to 5.7% at a heating temperature of 150 °C, that is, the application of a fluoroplastic coating on the outer wall of the cylinder sleeve does not lead to a change in the heat stress of the cylinder sleeve and will not affect the heat balance of the internal combustion engine. Thus, the obtained theoretical dependences make it possible to establish and justify not only the properties of the anti-cavitation material, but also the thickness of its application to the outer surface of the cylinder sleeve.

The quality control technology of inner surface of valve sleeve in abrasive flow machining

The quality control technology of inner surface of valve sleeve in abrasive flow machining

Calculations of electro contact baking of steel powders

This paper discusses the use of electro contact baking of steel powder on a bronze bushing. Its main design parameters are: taper angle of the matrix part - α, deg.; internal diameter of the matrix - D, mm; length of the cylindrical deforming belt - L, mm. To prevent melting of the surface of the restored bronze part, a special electrode was used, which made it possible to bake metal powders onto the bronze surface without melting the part to be restored. The diameter of the crimp die is defined as the difference between the outer diameter of the sleeve before compression and the sum of the wear on the inner surface of the bronze sleeve and the allowance for machining to obtain the nominal size of the inner diameter of the sleeve.

Comprehensive study of the process of cutting screw grooves on the inner surface of a cylindrical steel sleeve with rotary cutting mandrels

The paper presents the results of a comprehensive study of the process of cutting helical internal grooves on the basis of computer simulation in order to establish the influence of technological parameters of cutting on the forming force. Researches of cutting of screw grooves on thinwalled steel sleeves by a cutting mandrel with various cutting speeds have been carried out. The method of processing internal screw grooves on machines with simple kinematics is presented. The dependences of the influence of cutting rates on implementation of the hidden kinematical connection are established. Graphs reflecting the dependence of the cutting rate on the angle of inclination of the cut helical groove are constructed, and a regression equation is obtained describing the dependence of the studied factors on the axial force. Ranges of cutting rates are established, allowing to provide the maximum productivity at various angles of the spiral inclination. The results of processing the experimental data of the study of the influence of tool geometrical parameters on the forming force when cutting helical grooves on the inner surface of the cylindrical shell are shown. Levels of change of factors, variance of experiment results on each of experiments are defined. The regression coefficients are calculated, the regression equation is compiled, the variance of model adequacy is estimated and adequacy of the regression equation is checked, the nature of infl uence of interaction of cutting rate parameters, front angle and the allowable allowance on the forming force is determined. Based on the results of modeling using the Maple program, a regression equation was obtained that reflects dependence of influence of factors on the axial force per tool tooth, dependence of the influence of the studied factors on the change in temperature in a cutting zone, and also constructed a temperature field reflecting the heat distribution in the processing zone on the example of one experiment. The study was performed with the financial support of the Russian Foundation for Basic Research within the research project No. 19-38-90057.

Development of a system for diagnosing bearing assemblies with polymer parts during operation

The object of research is the process of monitoring the limiting wear of polymer-composite bushings of the bearing unit of the parallelogram mechanism of seeding machines. This process is clearly manifested in determining the good condition of the moving joints of machines operating in severe operating conditions. The studies performed are based on the principle of breaking the active link. The diagnostics is based on this principle, which makes it possible to assert with sufficient accuracy about the failure of the control link of the mates of parts. The main hypothesis of the study is that by developing a diagnostic system based on the control of composite bushings, it is possible to determine the boundaries of the normal functioning of the sowing sections as a whole. The solution of this issue without intervention in the design of the sowing section itself is impossible. Since the material of the sleeve is a polymer composite, which has sufficient resistance not to pass an electric current, conditions are created for the implementation of the proposed diagnostic system. In this work, a regression model is built to control and identify changes in the lateral backlash from the operating time of the seeding complex. By analyzing the data obtained, it is possible to establish the relationship between the diagnostic parameter, namely, the fixation of the rupture of the active link passing near the working surface of the composite sleeve. The main limitations in the development of this diagnostic system are the boundaries of the control gaps in the mates, as well as the presence of dielectric materials for the control parts. In the case of a significant occurrence of an active rupture link or an incorrect selection of its required diameter, then this diagnostic method may work inappropriately and the diagnostic system becomes ineffective. The work reflects the timeliness and rationality of the developed diagnostic system. On the basis of such a diagnostic system, it is possible to create an automated diagnostic complex for monitoring the state of the parallelogram mechanisms of the seeding complex as a whole.

Repeatability of Freehand Implantations Supported with Universal Plastic Sleeves—In Vitro Study

Repeatability and precision are major factors which have an influence on final implant treatment results. The aim of this study was to evaluate the repeatability of freehand implant procedures assisted with special plastic sleeves which are placed on the drill to guarantee the proper mesiodistal distance from the landmark’s surface. Patient data required for implant treatment, including images of mandibles from CBCT scans and virtual models of soft tissues and teeth, were used to prepare complete virtual models of patient clinical conditions. The models were saved as STL files and 3D printed in five copies. Drilling procedures were done at positions 37, 46 and 47. Each model was scanned with pins in the osteotomies and compared using digital aligning of the models’ surfaces. The average deviation was −1.38 ± 1.4 mm. Average deviations on guide pins placed at position 37 were −0.46 ± 0.59 mm, at position 46 were −1.46 ± 0.88 mm (landmark’s surface of both: distal tooth’s surface), and at position 47 were the highest: −2.69 ± 1.62 mm (landmark’s surface: surface of plastic sleeve). The following conclusion was drawn: Using universal plastic sleeves could improve implant procedure precision especially in the case of partially edentulous patients.

MATHEMATICAL MODELING OF STRENGTH-DEFORMED CONDITION OF PIPE CONCRETE CONSTRUCTIONS AT SUSTAINABLE TEMPERATURE

The mathematical modeling of the thermo-stressed state of pipe-concrete structures under conditions of stationary thermal conductivity is carried out. During the study, the most common structural type of TBC was selected and mathematical models of the stress-strain state of TBA under heating conditions were taken into account, taking into account their geometric dimensions and thermophysical characteristics of metal and concrete. The main feature of the TBC study is that the heat exchange in the structure, as well as the corresponding force response, are investigated independently of each other, whereas the problem of fire resistance should be posed as a classical problem of elasticity, taking into account the mutual influence of temperature and mechanical stresses.
 In two-layer structures (concrete - metal), the largest radial stresses that occur in concrete work in tension. Tensile stresses occur in the thickness of the outer tube. The stresses occurring on the inner surface of the steel sleeve coincide with the stresses in the concrete. When approaching the outer surface, they decrease and on the surface r = R2 equal to zero. In the case where the coefficients of linear extension αt (i = 1, 2) are equal to each other, the maximum tensile stresses are reduced within 0≤r≤R1 .; if νi (i = 1, 2) within 0≤ r≤R2, the stresses will also decrease. Axial stresses work on compression. They reach maximum value in the outer shell. For equal values αt (1) = αt (2), the magnitude of the stresses does not change, and at ν1 = ν2 the stresses in the metal will decrease. Ring stresses in the region 0≤ r≤R1 are tensile stresses and in the region R1≤ r≤R2 are compression stresses, and the compression stresses are greater than the tensile stresses in concrete. For αt (1) = αt (2), the stresses in the concrete decrease and for ν1 = ν2.

Study of Voltage Distribution and Radial Electric Field under Different Pollution Conditions of 500kV MOA

The surface of the porcelain sleeve will be polluted by local environmental pollution and weather factors such as frost, rain and snow, because of the 500kV MOA is generally arranged outdoors. The surface flashover problem of the porcelain sleeve surface caused by contamination is similar to that of the insulator surface. It is a resistor column with three sections connected in series inside the arrester. The influence of surface contamination on the voltage distribution of the internal resistor and the radial electric field between the resistor and the porcelain sleeve remains to be studied. In this paper, ANSYS is used to establish a two-dimensional axisymmetric simulation model for the surface contamination of 500kV zinc oxide arrester. The electric field distribution of the surface of the arrester is cleaned, evenly polluted and the local drying zone appears. The results show that the uniform contamination is inside the arrester. The electric field has little influence, and the local drying zone will form a locally excessively high radial electric field between the resistor and the porcelain sleeve. Under the reference voltage, the radial electric field exceeds the corona starting field and causes corona discharge, and the acceleration resistor Deterioration of the sheet and the dielectric; the voltage of the resistor piece near the local drying zone is increased to a certain extent, which also accelerates the aging of the resistor chip and jeopardizes the safe and stable operation of the arrester

Analysis on an elevator brake magnetic sleeve

An elevator brake failed during use. Failure analysis was performed on magnetic sleeve of the elevator brake. The metallographic microstructure and SEM morphology of the elevator brake magnetic sleeve were investigated based on the optical microscope and scanning electron microscope analysis. The results showed that the entrance of foreign materials caused the extrusion wear to local area of the inner surface of the magnetic sleeve.

Research on the process of biomass compaction in the form of straw

The paper presents the examination of the degree of compaction of biomass material in the form of straw, depending on the temperature of the compaction process, the diameter of the pressing punch and the humidity of the compacted straw. The series of punch-sleeve assemblies characterized by the variable diameter of both the punch and the sleeve were used in the tests. For each diameter of the sleeve, a straw sample was compressed with a force suitable to obtain a compressive stress value in the sample cross section of 10 MPa. Each punch-sleeve assembly was adapted for installation on a strength machine, mounting temperature sensors and for mounting on the surface of a cylindrical sleeve, a coil heater. Wheat-rye straw was used in the research. The tests carried out are to constitute guidelines for the construction of biomass compaction machines.

Floating ring journal bearings of multilobe design in turbochargers

The floating ring bearings system of turbocharger operates at high rotational speeds and high temperatures on the inlet of exhaust gases. Usually, such system applies the cylindrical profile of floating ring and stationary sleeve. The changes of the geometry of inner sliding surface of stationary sleeve as well as external or inner sliding surface of floating ring into multilobe surfaces allow for obtaining additional operation properties. It can be expected the changes in the static and dynamic characteristics of bearing what results in higher speeds of operation and better stability. The paper considers application of multilobe sliding surfaces in the design of turbocharger as well as the computation possibilities of such design bearings. Exemplary results of the computation of static and dynamic characteristics for the chosen types of multilobe bearings support their application in high speed rotating machinery including the floating ring bearings of turbochargers. Applied code and the results of this work allow calculating the stability of rotors operating in the bearings with the turbulent model of oil film and particularly the high speed floating ring bearings.

Cavitation and slip performance analysis of dynamically loaded sleeve bearing

The generalized Reynolds equation of dynamically loaded sleeve bearing is established based on mass conservation boundary condition and wall-slip effect. The cavitation migration and flow velocity of spiral oil wedge bearing for different times are computed, using the finite difference method by solving the Reynolds equation of four slip states with cavitation effect. The results show that the cavitation area with cavitation effect and wall slip decreases compared to the cavitation area without regard to cavitation effect and wall slip. As time goes, the slip location at the surface of axis and sleeve moves generally along the rotation direction of axis, and the region of slip changes.

Surgical ligation of spinal dural arteriovenous fistula.

Spinal dural arteriovenous fistulas (SDAVFs) are abnormal arteriovenous shunts between a radicular artery and the radicular vein, located in the dorsal surface of the dura sleeve, which drains in a retrograde manner into the coronal venous plexus of the spinal cord without an interposed capillary network. This result is a venous hypertension that reduces spinal cord perfusion and leads to ischemia and edema. Spontaneous resolution is extremely rare and, once symptomatic, the typical course is further progression with increased neurological impairment. Therefore, once a fistula is diagnosed, treatment is recommended. The fistula is placed at the level of intervertebral foramen and surgical ligation is performed through a laminectomy. After dural opening, the area is inspected, and the arterialized vein is identified and ligated. Laminectomy and arteriovenous fistula ligation is a safe and reliable approach for accessing and treating spinal dural arteriovenous fistulas.

Ceramic Bearings with Titanium Adapter Sleeves Implanted During Revision Hip Arthroplasty Show Minimal Fretting or Corrosion: a Retrieval Analysis.

The BIOLOX® option system, consisting of a BIOLOX® delta ceramic femoral head with a titanium alloy adapter sleeve, is being increasingly utilized in revision hip arthroplasty. The sleeve protects the ceramic head from fracture and improper motion about the stem trunnion when a damaged trunnion is encountered at revision surgery. Corrosion and fretting due to metal-metal contact at the taper region of hip prosthesis create the potential of causing periprosthetic osteolysis and adverse local tissue reactions. The objective of this study was to identify the type and extent of damage to retrieved sleeves and ceramic heads to determine their in vivo performance. Twenty-four ceramic heads with titanium alloy sleeves were examined. The articular and taper surfaces for each ceramic head were assessed for metal transfer using a subjective grading system. All surfaces of the 24 titanium sleeves and stem trunnions (only available for 7 of 24 cases) were assessed for corrosion and fretting using an established grading system. Scanning electron microscopy and energy dispersive X-ray analysis were conducted on representative sample of sleeves. Fretting and corrosion were higher at the inner surface of the taper sleeve than the outer sleeve. Mean fretting scores at the inner taper and outer taper sleeve surfaces were 1.8 and 1.2, respectively. The mean corrosion score at the inner taper surface was 1.8; no corrosion was observed on the outer surface of any taper sleeve. SEM and EDS analyses provided further indications of low levels of damage. Fretting and corrosion were less severe than previously reported for conventional THA metal-metal taper connections, indicating that a ceramic head and titanium sleeve is a safe alternative in revision THA.

Wear Resistance of Piston Sleeve Made of Layered Material Structure: MMC A356R, Anti-Abrasion Layer and FGM Interface

Abstract The aim of this paper is the numerical analysis of the one of main part of car engine – piston sleeve. The first example is for piston sleeve made of metal matrix composite (MMC) A356R. The second improved material structure is layered. Both of them are comparison to the classical structure of piston sleeve made of Cr-Ni stainless steel. The layered material structure contains the anti-abrasion layer at the inner surface of piston sleeve, where the contact and friction is highest, FGM (functionally graded material) interface and the layer of virgin material on the outer surface made of A356R. The complex thermo-elastic model with Archard's condition as a wear law is proposed. The piston sleeve is modelling as a thin walled cylindrical axisymmetric shell. The coupled between the formulation of thermo-elasticity of cylindrical axisymmetric shell and the Archard’s law with functionally changes of local hardness is proposed.

Preparation of a Clamp Sleeve Spare Parts for Crimping Machine Using Low Carbon Steel Material by Heat Treatment Process

In Metered Dose Inhaler plant of pharmaceutical industries of Bangladesh, clamp sleeve spare part used in crimping machine collected from foreign countries. The clamp sleeve presses the crimping tong containing aluminium can to crimp the body with head. Due to the continuous action of the clamp sleeve to the crimping tong the inner surface of the clamp sleeve get corroded. The clamp sleeve is replaced when crimping appearance fails to meet compliance. In this Research an experimental work relating to improve the mechanical properties of locally available low carbon steel material by heat treatment process have been carried out to replace the spare parts of clamp sleeve which is collected from foreign countries. The mechanical properties have been studied on before and after heat treatment. After heat treatment, it is found that hardness, impact and compressive strength of heat treated specimen has been developed drastically as compared to that of before heat treatment. Finally, the properties of improved material has been determined and used to the machine functional area to check the performance of the clamp sleeve. After consecutive operation of the machine it can be concluded that the improved clamp sleeve meets the user requirement with compliance of smooth crimping quality and locally available low carbon steel material can be used for the preparation of clamp sleeve spare parts of crimping machine for pharmaceutical industry using the proper heat treatment process which might be helpful to save huge cost and time rather than collected from foreign countries.